Abstract
Interdiffusion phenomena between WC-10%Co alloys and carbon steels were examined in relation to their carbon contents. Two kinds of cemented carbides, i.e., low carbon and high carbon two-phase alloys were coupled and brazed at temperatures of 1100°∼1300°C for 1 hr with steels having various carbon contents. Then, hardness measurements, microstructure observations and X-ray analyses were made on the diffusion layers. Main results obtained were as follows:
(1) As for the diffusing direction of carbon, the mechanism which is generally accepted that carbon diffuses from cemented carbides to steels was not always confirmed. The inverse diffusion from steels to cemented carbides was observed when the carbon content of steels exceeded about 0.8%.
(2) Complex carbide was formed in the cemented carbide side, only when the diffusing direction of carbon was from cemented carbides to steels. The carbide was identified to be M6C type.
(3) It seems that the properties of cemented carbides are deteriorated due to the following facts; (i) Harmful phases, i.e., M6C, M23C6 or free carbon phase, were formed in cemented carbides according to the coupling conditions. (ii) Cobalt diffused from cemented carbides and at the same time iron diffused in.
(4) The diffusing amount of cobalt or iron appeared to be strongly affected by the carbon contents of coupled materials.
